Image transmitting/receiving system, image transmitting apparatus, received image displaying apparatus, wireless control apparatus, and image transmitting/receiving method

ABSTRACT

A received image displaying apparatus comprises: a wireless communication unit that wirelessly receives the frame images transmitted by the image transmitting apparatus with which the received image displaying apparatus has established a connection of wireless communication; and a displaying unit that displays the frame images, which were wirelessly received by the wireless communication unit, in an order in which the frame images were captured. At least one of the image transmitting apparatus and the received image displaying apparatus comprises: a reference sync signal generating unit that generates the reference sync signals; and a control unit that, if the wireless communication unit has received no reference sync signals for a certain time interval, controls the reference sync signal generating unit to generate reference sync signals and that further controls the wireless communication unit to wirelessly transmit the reference sync signals to the other apparatus included in the image transmitting/receiving system.

CROSS REFERENCE IX) RELATED APPLICATIONS

This application is a continuation application based on a PCT PatentApplication No, PCT/JP2012/054694, filed Feb. 27, 2012, whose priorityis claimed on Japanese Patent Application No. 2011-087534, filed Apr.11, 2011, the entire content of which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image transmitting/receiving system,an image transmitting apparatus, a received image displaying apparatus,a wireless control apparatus, and an image transmitting/receivingmethod.

2. Description of the Related Art

All patents, patent applications, patent publications, scientificarticles, and the like, which will hereinafter be cited or identified inthe present application, will hereby be incorporated by reference intheir entirety in order to describe more fully the state of the art towhich the present invention pertains.

In recent years, a technology in which a high quality image called highvision is transmitted in a wireless manner between an image source of aDVD deck, an HDD recorder, a set-top box, or a specific image signalgenerating apparatus for business and a monitor mounted on a wall andthe like in a relatively narrow range of a house, an office, and aspecific work site has been put to practical use. Furthermore, adistribution method in which reproduction is not disconnected even whena connected device is changed during the streaming distribution of imagecontent has been known (for example, refer to Japanese Unexamined PatentApplication, First Publication No. 2010-50930). This represents thatconnection switching is performed after setting with a device to beconnected is performed while performing bi-directional communication.

SUMMARY

The present invention provides an image transmitting/receiving system,an image transmitting apparatus, a received image displaying apparatus,a wireless control apparatus, and an image transmitting/receivingmethod, by which it is possible to perform the switching of acommunication connection without influencing the transmission/receptionof an image signal.

According to a first aspect of the present invention, an imagetransmitting/receiving system may include a plurality of imagetransmitting apparatuses which continuously wirelessly transmitcontinuously captured frame images in a captured order and a pluralityof received image displaying apparatuses which continuously wirelesslyreceive the frame images continuously wirelessly transmitted by theplurality of image transmitting apparatuses and continuously display thereceived frame images in the captured order. The image transmittingapparatus may include: a first wireless communication unit whichwirelessly transmits the frame image to the received image displayingapparatus, which has established a wireless communication connectionwith the image transmitting apparatus, in synchronization with areference synchronization signal. The received image displayingapparatus includes: a second wireless communication unit whichwirelessly receives the frame images transmitted from the imagetransmitting apparatus having established a wireless communicationconnection with the received image displaying apparatus; and a displayunit which displays the frame images, which have been wirelesslyreceived in the wireless communication unit, in the captured order ofthe frame images. At least one apparatus of the image transmittingapparatus and the received image displaying apparatus included in theimage transmitting/receiving system includes: a referencesynchronization signal generation unit which generates a referencesynchronization signal; and a control unit which controls the referencesynchronization signal generation unit to generate the referencesynchronization signal and controls the first wireless communicationunit to wirelessly transmit the reference synchronization signal toanother apparatus included in the image transmitting/receiving systemwhen the second wireless communication unit does not receive thereference synchronization signal within a constant period. At least oneof the image transmitting apparatus and the received image displayingapparatus includes: a blanking interval recognition unit whichrecognizes a vertical blanking interval of the frame image; and adisconnection control unit which controls the first or second wirelesscommunication unit to start, a disconnection process of wirelesscommunication within a period of the vertical blanking intervalrecognized by the blanking interval recognition unit.

According to a second aspect of the present invention, in the imagetransmitting/receiving system of the first aspect, the disconnectioncontrol unit provided in the at least one of the image transmittingapparatus and the received image displaying apparatus may control thefirst or second wireless communication unit not to perform thedisconnection process outside of the vertical blanking interval.

According to a third aspect of the present invention, in the imagetransmitting/receiving system of the first aspect, the blanking intervalrecognition unit may recognize the vertical blanking interval based onthe frame image or the reference synchronization signal.

According to a fourth aspect of the present invention, an imagetransmitting apparatus in an image transmitting/receiving system mayinclude a plurality of image transmitting apparatuses which continuouslywirelessly transmit continuously captured frame images in a capturedorder and a plurality of received image displaying apparatuses whichcontinuously wirelessly receive the frame images continuously wirelesslytransmitted by the plurality of image transmitting apparatuses andcontinuously display the received frame images in the captured order.The image transmitting apparatus may include: a wireless communicationunit which wirelessly transmits the frame image to the received imagedisplaying apparatus, which has established a wireless communicationconnection with the image transmitting apparatus, in synchronizationwith a reference synchronization signal; a reference synchronizationsignal generation unit which generates a reference synchronizationsignal; a control unit which controls the reference synchronizationsignal generation unit to generate the reference synchronization signaland controls the wireless communication unit to wirelessly transmit thereference synchronization signal to another apparatus included in theimage transmitting/receiving system when the wireless communication unitdoes not receive the reference synchronization signal within a constantperiod; a blanking interval recognition unit which recognizes a verticalblanking interval of the frame image; and a disconnection control unitwhich controls the wireless communication unit to start a disconnectionprocess of wireless communication within a period of the verticalblanking interval recognized by the blanking interval recognition unit.

According to a fifth aspect of the present invention, in the imagetransmitting apparatus of the fourth aspect the control unit may controlthe wireless communication unit to transmit the referencesynchronization signal within the vertical blanking interval.

According to a sixth aspect of the present invention, the imagetransmitting apparatus of the fourth aspect may further include adetection unit which detects a plurality of communication channels usedwhen another image transmitting apparatus included in the imagetransmitting/receiving system wirelessly transmits the frame image. Thecontrol unit may control the wireless communication unit to transmit thereference synchronization signal through each communication channeldetected by the detection unit.

According to a seventh aspect of the present invention, in the imagetransmitting apparatus of the sixth aspect when the detection unitdetects the plurality of communication channels, the control unit maycontrol the wireless communication unit to transmit the referencesynchronization signal through only some of the plurality ofcommunication channels detected by the detection unit, in a singlevertical blanking interval.

According to an eighth aspect of the present invention, in the imagetransmitting apparatus of the seventh aspect, the control unit maycontrol the wireless communication unit to transmit the referencesynchronization signal through one of the plurality of communicationchannels detected by the defection unit, in the single vertical blankinginterval.

According to a ninth aspect of the present invention, the imagetransmitting apparatus of the fourth aspect may further include aninstruction receiving unit which receives an instruction for addition,modification, and deletion of a transmission destination of the frameimage, and, when the instruction receiving unit receives theinstruction, the disconnection control unit may control the wirelesscommunication unit to start the disconnection process.

According to a tenth aspect of the present invention, the imagetransmitting apparatus of the ninth aspect may further include anoperation unit which receives an operation by a user, and theinstruction receiving unit may receive the instruction based on theoperation received in the operation unit.

According to a eleventh aspect of the present invention, in the imagetransmitting apparatus of the ninth aspect, the instruction receivingunit may receive the instruction from another apparatus included in theimage transmitting/receiving system through the communication unit.

According to a twelfth aspect of the present invention, in the imagetransmitting apparatus of the fourth aspect the disconnection controlunit may control the wireless communication unit not to perform thedisconnection process outside of the vertical blanking interval.

According to a thirteenth aspect of the present invention, a receivedimage displaying apparatus in an image transmitting/receiving system mayinclude a plurality of image transmitting apparatuses which continuouslywirelessly transmit continuously captured frame images in a capturedorder and a plurality of received image displaying apparatuses whichcontinuously wirelessly receive the frame images continuously wirelesslytransmitted by the plurality of image transmitting apparatuses andcontinuously display the received frame images in the captured order.The received image displaying apparatus may include: a wirelesscommunication unit which wirelessly receives the frame images from theimage transmitting apparatus having established a wireless communicationconnection with the received image displaying apparatus; a display unitwhich displays the frame images wirelessly received in the wirelesscommunication unit, in a captured order of the frame images; a referencesynchronization signal generation unit which generates a referencesynchronization signal; a control unit which controls the referencesynchronization signal generation unit to generate the referencesynchronization signal and controls the wireless communication unit towirelessly transmit the reference synchronization signal to anotherapparatus included in the image transmitting/receiving system when thewireless communication unit does not receive the referencesynchronization signal within a constant period; a blanking intervalrecognition unit which recognizes a vertical blanking interval of theframe image; and a disconnection control unit which controls thewireless communication unit to start a disconnection process of wirelesscommunication within a period of the vertical blanking intervalrecognized by the blanking interval recognition unit.

According to a fourteenth aspect of the present invention, in thereceived image displaying apparatus of the thirteenth aspect, thewireless communication unit may wirelessly receive the frame images in aform of packet data, and the reference synchronization signal generationunit may generate the reference synchronization signal based on packetdata, which indicates final data of each frame of the frame images,among the packet data wirelessly received in the wireless communicationunit.

According to a fifteenth aspect of the present invention, in thereceived image displaying apparatus of the thirteenth aspect, thecontrol unit may control the wireless communication unit to wirelesslytransmit the reference synchronization signal generated by the referencesynchronization signal generation unit according to packet dataindicating a response for packet data, which indicates final data ofeach frame of the frame images, among the packet data wirelesslyreceived in the wireless communication unit.

According to a sixteenth aspect of the present invention, in thereceived image displaying apparatus of the thirteenth aspect, thewireless communication unit may wirelessly receive the frame images in aform of packet data, and the blanking interval recognition unit mayrecognize the vertical blanking interval of the frame image based onwhether the packet data wirelessly received in the wirelesscommunication unit is packet data indicating final data of each frame ofthe frame images.

According to a seventeenth aspect of the present invention, the receivedimage displaying apparatus of the thirteenth aspect may further includea detection unit which detects a plurality of communication channelsused when another image transmitting apparatus included in the imagetransmitting/receiving system wirelessly transmits the frame image, andthe control unit may control the wireless communication unit to transmitthe reference synchronization signal through each communication channeldetected by the detection unit.

According to a eighteenth aspect of the present invention, in thereceived image displaying apparatus of the seventeenth aspect, when thedetection unit detects the plurality of communication channels, thecontrol unit may control the wireless communication unit to transmit thereference synchronization signal through only some of the plurality ofcommunication channels detected by the detection unit, in a singlevertical blanking interval.

According to a nineteenth aspect of the present invention, in thereceived image displaying apparatus of the eighteenth aspect, thecontrol unit may control the wireless communication unit to transmit thereference synchronization signal through one of the plurality ofcommunication channels detected by the detection unit, in the singlevertical blanking interval.

According to a twentieth aspect of the present invention, the receivedimage displaying apparatus of the thirteenth aspect may further includean instruction receiving unit which receives an instruction foraddition, modification, and deletion of a transmission destination ofthe frame image, and, when the instruction receiving unit receives theinstruction, the disconnection control unit may control the wirelesscommunication unit to start the disconnection process.

According to a twenty-first aspect of the present invention, thereceived image displaying apparatus of the twentieth aspect may furtherinclude an operation unit which receives an operation by a user, and theinstruction receiving unit receives the instruction based on theoperation received in the operation unit.

According to a twenty-second aspect of the present invention, in thereceived image displaying apparatus of the twentieth aspect, theinstruction receiving unit may receive the instruction from anotherapparatus included in the image transmitting/receiving system throughthe communication unit.

According to a twenty-third aspect of the present invention, in thereceived image displaying apparatus of the thirteenth aspect, thedisconnection control unit may control the wireless communication unitnot to perform the disconnection process outside of the verticalblanking interval.

According to a twenty-fourth aspect of the present invention, a wirelesscontrol apparatus in an image transmitting/receiving system may includea plurality of image transmitting apparatuses which continuouslywirelessly transmit continuously captured frame images in a capturedorder, a plurality of received image displaying apparatuses whichcontinuously wirelessly receive the frame images continuously wirelesslytransmitted by the plurality of image transmitting apparatuses andcontinuously display the received frame images in the captured order,and the wireless control apparatus which instructs the imagetransmitting apparatus to wirelessly communicate with the received imagedisplaying apparatus serving as a transmission destination of the frameimage and instructs the received image displaying apparatus towirelessly communicate with the image transmitting apparatus serving asa transmission source of the frame image. The wireless control apparatusmay include: a wireless communication unit which wirelessly communicateswith the image transmitting apparatus and the received image displayingapparatus; a reference synchronization signal generation unit whichgenerates a reference synchronization signal; and a control unit whichcontrols the reference synchronization signal generation unit togenerate the reference synchronization signal and controls the wirelesscommunication unit to wirelessly transmit the reference synchronizationsignal to another apparatus included in the image transmitting/receivingsystem when the wireless communication unit does not receive thereference synchronization signal within a constant period.

According to a twenty-fifth aspect of the present invention, thewireless control apparatus of the twenty-fourth aspect may include: aninstruction receiving unit which receives an instruction for addition,modification, and deletion of a combination of the apparatus serving asthe transmission destination of the frame image and the apparatusserving as the transmission source of the frame image; and adisconnection instruction control unit which controls the wirelesscommunication unit to transmit an instruction for starting adisconnection process of wireless communication to the apparatus of thecombination received in the instruction receiving unit when theinstruction receiving unit receives the instruction.

According to a twenty-sixth aspect of the present invention, an imagetransmitting/receiving method in an image transmitting/receiving systemmay include a plurality of image transmitting apparatuses whichcontinuously wirelessly transmit continuously captured frame images in acaptured order and a plurality of received image displaying apparatuseswhich continuously wirelessly receive the frame images continuouslywirelessly transmitted by the plurality of image transmittingapparatuses and continuously display the received frame images in thecaptured order. The image transmitting/receiving method may include: awireless transmission step of wirelessly transmitting, by a wirelesscommunication unit of the image transmitting apparatus, the frame imageto the received image displaying apparatus, which has established awireless communication connection with the image transmitting apparatus,in synchronization with a reference synchronization signal; a wirelessreception step of wirelessly receiving, by a wireless communication unitof the received image displaying apparatus, the frame image transmittedfrom the image transmitting apparatus having established a wirelesscommunication connection with the received image displaying apparatus; adisplay step of displaying, by a display unit of the received imagedisplaying apparatus, the frame images, which have been wirelesslyreceived in the wireless communication unit, in the captured order ofthe frame images; a reference synchronization signal generation step ofgenerating, by a reference synchronization signal generation unit of atleast one of the image transmitting apparatus and the received imagedisplaying apparatus included in the image transmitting/receivingsystem, a reference synchronization signal; a control step ofcontrolling, by a control unit, of at least one of the imagetransmitting apparatus and the received image displaying apparatusincluded in the image transmitting/receiving system, the referencesynchronization signal generation unit to generate the referencesynchronization signal and controlling the wireless communication unitto wirelessly transmit the reference synchronization signal to anotherapparatus included in the image transmitting/receiving system when thewireless communication unit does not receive the referencesynchronization signal within a constant period; a blanking intervalrecognition step of recognizing, by a blanking interval recognition unitof at least one of the image transmitting apparatus and the receivedimage displaying apparatus, a vertical blanking interval of the frameimage; and a disconnection control step of controlling, by adisconnection control unit of at least one of the image transmittingapparatus and the received image displaying apparatus, the wirelesscommunication unit to start a disconnection process of wirelesscommunication within a period of the vertical blanking intervalrecognized by the blanking interval recognition unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The above features and advantages of the present invention will be moreapparent from the following description of certain preferred embodimentstaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram representing the configuration of an imagetransmitting/receiving system in accordance with a first preferredembodiment of the present invention.

FIG. 2 is a block diagram representing the configuration of an imagetransmitting apparatus in accordance with a first preferred embodimentof the present invention.

FIG. 3 is a block diagram representing the configuration of a receivedimage displaying apparatus in accordance with a first preferredembodiment of the present invention.

FIG. 4 is a schematic diagram representing the data structure of areference synchronization signal in accordance with a first preferredembodiment of the present invention.

FIG. 5 is a schematic diagram representing timings at which an imagetransmitting apparatus transmits a reference synchronization signal inaccordance with a first preferred embodiment of the present invention.

FIG. 6 is a schematic diagram representing an example of a pairing listin accordance with a first preferred embodiment of the presentinvention.

FIG. 7 is a schematic diagram representing an example of a pairing listin accordance with a first preferred embodiment of the presentinvention.

FIG. 8 is a flowchart representing an operation procedure of an imagereceiving apparatus in accordance with a first preferred embodiment ofthe present invention.

FIG. 9 is a schematic diagram representing image signal transmissiontimings and blanking intervals in accordance with a first preferredembodiment of the present invention.

FIG. 10 is a sequence diagram representing an operation procedure whenswitching a connection between an image transmitting apparatus and areceived image displaying apparatus in accordance with a firstpreferred, embodiment of the present invention.

FIG. 11 is a flowchart representing an operation procedure of an imagereceiving apparatus in accordance with a second preferred embodiment ofthe present invention.

FIG. 12 is a schematic diagram representing the data, configuration of areference synchronization signal in accordance with a third preferredembodiment of the present invention.

FIG. 13 is a schematic diagram representing timings at which acommunication control unit transmits a reference synchronization signalin accordance with a third preferred embodiment of the presentinvention.

FIG. 14 is a flowchart representing an operation procedure of a receivedimage displaying apparatus in accordance with a third preferredembodiment of the present invention.

FIG. 15 is a sequence diagram representing an operation procedure whenswitching a connection between an image transmitting apparatus and areceived image displaying apparatus in accordance with a third preferredembodiment of the present invention.

FIG. 16 is a flowchart representing an operation procedure of an imagereceiving apparatus in accordance with a fourth preferred embodiment ofthe present invention.

FIG. 17 is a schematic diagram representing the configuration of animage transmitting/receiving system in accordance with a fifth preferredembodiment of the present invention.

FIG. 18 is a block diagram representing the configuration of a remotecontrol apparatus in accordance with a fifth preferred embodiment of thepresent invention.

FIG. 19 is a flowchart representing an operation procedure of a remotecontrol apparatus in accordance with a fifth preferred embodiment of thepresent invention.

FIG. 20 is a sequence diagram representing an operation procedure whenswitching a connection between an image transmitting apparatus and areceived image displaying apparatus in accordance with a fifth preferredembodiment of the present invention.

FIG. 21 is a schematic diagram representing the configuration of aconventionally known image transmitting/receiving system.

FIG. 22 is a schematic diagram representing image signal transmissiontimings and blanking intervals in a conventionally known imagetransmitting/receiving system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be now described herein with reference toillustrative preferred embodiments. Those skilled in the art willrecognize that many alternative preferred embodiments can beaccomplished using the teaching of the present invention and that thepresent invention is not limited to the preferred embodimentsillustrated for explanatory purpose.

First Preferred Embodiment

Hereinafter, a first preferred embodiment of die present invention isdescribed with reference to the accompanying drawings. In the presentpreferred embodiment, one of image transmitting apparatuses included inan image transmitting/receiving system transmits a referencesynchronization signal indicating a transmission timing of an imagesignal (a frame image) to other image transmitting apparatuses. Then,all image transmitting apparatuses included in the imagetransmitting/receiving system transmit an image signal based on thereference synchronization signal. In this way, all the imagetransmitting apparatuses included in the image transmitting/receivingsystem are able to synchronize a timing at which the image signal istransmitted with a timing (a blanking interval, a vertical blankinginterval) at which no image signal is transmitted. Furthermore, in thecase of switching a connection destination apparatus, the imagetransmitting apparatuses and received image displaying apparatusesincluded in the image transmitting/receiving system perform thetransmission/reception of data required in order to switch theconnection destination apparatus during the blanking interval.Consequently, it is possible to perform the switching of a communicationconnection without influencing the transmission/reception of the imagesignal.

FIG. 1 is a schematic diagram representing the configuration of an imagetransmitting/receiving system in accordance with the present preferredembodiment. In the illustrated example, an image transmitting/receivingsystem 1 includes image transmitting apparatuses 10-1 to 10-3 andreceived image displaying apparatuses 20-1 to 20-4. The imagetransmitting apparatuses 10-1 to 10-3 are apparatuses that continuouslywirelessly transmit continuously captured image signals in a capturedorder. The received image displaying apparatuses 20-1 to 20-4 areapparatuses that continuously receive the image signals and continuouslydisplay the received image signals in the captured order.

Next, the configuration of the image transmitting apparatus 10 will bedescribed. FIG. 2 is a block diagram representing the configuration ofthe image transmitting apparatus 10 in accordance with the presentpreferred embodiment. In the illustrated example, the image transmittingapparatus 10 includes a moving image input unit 110, a storage unit 120,an image signal generation unit 130, a reference synchronization signalgeneration unit 140, a control unit 150, a terminal detection unit 160,a communication control unit 170 (a disconnection control unit), awireless unit 180 (a wireless communication unit), an instruction inputunit 190 (an operation unit), and a display unit 200.

The moving image input unit 110 receives moving image data to betransmitted. An example of the moving image input unit 110 includes animaging device including an imaging element such as a CCD (ChargedCoupled Device), a moving image recording device such as an HDD (HardDisk Drive) or DVD (Digital Versatile Disc), and a moving image inputmeans represented by DVI (Digital Visual Interface), HDMI (registeredtrademark) (High-Definition Multimedia Interface) and the like.

The storage unit 120 includes an image holding unit 121 and a listmanagement unit 122. The image holding unit 121 stores the moving imagedata input to the moving image input unit 110. The list management unit122 stores a pairing list indicating combinations of the imagetransmitting apparatuses 10 and the received image displayingapparatuses 20, which perform communication. The image signal generationunit 130 generates an image signal by converting the moving image datainto a format in which a moving image of one frame is generated for eachconstant time, which is represented by NTSC (National Television Systemcommittee). PAL (Phase Alternating Line), or BT656. The referencesynchronization signal generation unit 140 generates a referencesynchronization signal indicating a transmission timing of an imagesignal in all the image transmitting apparatuses 10 included in theimage transmitting/receiving system 1.

The control unit 150 performs the control of each element provided inthe image transmitting apparatuses 10. Furthermore, the control unit 150includes a recognition unit 151 (a blanking interval recognition unit)that recognizes a timing at which an image signal is transmitted, and ablanking interval which indicates a timing at which control data istransmitted, based on the reference synchronization signal. The terminaldetection unit 160 searches for another apparatus included in the imagetransmitting/receiving system 1. The communication control unit 170performs the communication control (a baseband process) of an imagesignal (an image signal packet) or control data (a control packet). Thewireless unit 180 includes a transmission unit 181 and a reception unit182. The transmission unit 181 wirelessly transmits data, such as animage signal or control data, to another apparatus through an antenna(not illustrated). The reception unit 182 wirelessly receives data,which is wirelessly transmitted from another apparatus, through anantenna (not illustrated). The instruction input unit 190 includes akeyboard, a switch and the like, and receives instruction input from auser. The display unit 200 includes a liquid crystal display and thelike, and displays various types of information.

In addition, in the present preferred embodiment, in order for theterminal detection unit 160 to detect a terminal, sincetransmission/reception data is controlled to have no influence on thetransmission of an image signal, the wireless unit 180 used in thetransmission/reception of an image signal is shared. However, a wirelessunit dedicated for the terminal detection unit 160 may be provided.

Next, the configuration of the received image displaying apparatus 20will be described. FIG. 3 is a block diagram representing theconfiguration of the received image displaying apparatus 20 inaccordance with the present preferred embodiment. In the illustratedexample, the received image displaying apparatus 20 includes a wirelessunit 300 (a wireless communication unit), a communication control unit310 (a disconnection control unit), a control unit 320, a referencesynchronization signal generation unit 330, a terminal detection unit340, a storage unit 350, an instruction input unit 360, and a displayunit 370.

The wireless unit 300 includes a transmission unit 301 and a receptionunit 302. The transmission unit 301 wirelessly transmits data to anotherapparatus through an antenna (not illustrated). The reception unit 302wirelessly receives data, which is wirelessly transmitted from anotherapparatus, through an antenna (not illustrated). The communicationcontrol unit 310 performs the communication control (a baseband process)of an image signal (an image signal packet) or control data (a controlpacket). The control unit 320 performs the control of each elementprovided in the received image displaying apparatus 20. Furthermore, thecontrol unit 320 includes a recognition unit 321 (a blanking intervalrecognition unit). The recognition unit 321 recognizes a blankinginterval indicating a timing at which the control data is transmitted,and further recognizes a final packet in each frame of the image signalreceived in the reception unit 302. In addition, when the recognitionunit 321 recognizes the final packet, the transmission unit 302 hasfunctions of transmitting an ACK signal for the final packet, andtransmitting a reference synchronization signal generated by thereference synchronization signal generation unit 330 after transmittingthe ACK signal.

The reference synchronization signal generation unit 330 generates areference synchronization signal indicating a transmission timing of animage signal in all the image transmitting apparatuses 10 included inthe image transmitting/receiving system 1. The terminal detection unit340 searches for another apparatus included in the imagetransmitting/receiving system 1. The storage unit 350 stores data usedin the received image displaying apparatus 20. The instruction inputunit 360 includes a keyboard, a switch and the like, and receivesinstruction input from a user. The display unit 370 includes a liquidcrystal display and the like, and displays an image (a moving image)based on an image signal.

Next, a data structure of the reference synchronization signal will bedescribed. FIG. 4 is a schematic diagram representing the data structureof the reference synchronization signal in accordance with the presentpreferred embodiment. In the illustrated example, the referencesynchronization signal has data items of a header BlankSync, adestination address, a transmission source address, t_a, t_b, and an FCS(Frame Check Sequence). The header stores data, indicating the referencesynchronization signal, and the like. As the destination address, anaddress of an apparatus to which the reference synchronization signal istransmitted is stored. The destination may be a broadcast address or amulticast address for a specific group. As the transmission sourceaddress, an address of a transmission source apparatus of the referencesynchronization signal is stored. As the t_a, a period t_a indicating apredetermined period from a start time point of a blanking interval isstored. As the t_b, a period t_b indicating a predetermined period froma time point at which the reference synchronization signal has beentransmitted is stored. The FCS stores data for error detection and errorcorrection of the reference synchronization signal.

Next, details of timings at which the image transmitting apparatus 10transmits the reference synchronization signal will be described. FIG. 5is a schematic diagram representing timings at which the imagetransmitting apparatus 10 transmits the reference synchronization signalin accordance with the present preferred embodiment. In addition, ahorizontal axis denotes time.

As illustrated in FIG. 5, the image transmitting apparatus 10 transmitsthe reference synchronization signal at a time point at which thepredetermined period t_a has passed from a time point at which ablanking period has started. Furthermore, the image transmittingapparatus 10 waits for a process until the predetermined period t_bpasses from the time point at which the reference synchronization signalhas been transmitted, and then transmits an image signal of one frame.In addition, the timing at which the image transmitting apparatus 10transmits the reference synchronization signal, for example, may bepositioned immediately after the blanking period has started, or may bewithin the blanking period. However, the timing at which the imagetransmitting apparatus 10 transmits the reference synchronization signalis assumed to be a constant timing each time.

In addition, when generating the reference synchronization signal, thereference synchronization signal generation unit 140 stores, in thereference synchronization signal, information on one or both of theperiod t_a indicating the predetermined period from the time point atwhich the blanking interval has started and the period t_b indicatingthe predetermined period from the time point at which the referencesynchronization signal has been transmitted. Consequently, an apparatushaving received the reference synchronization signal is able torecognize the timing at which the blanking interval starts and thetiming at which the blanking interval ends.

Next, the data structure of a pairing list indicating combinations ofthe image transmitting apparatuses 10 and the received image displayingapparatuses 20 which perform communication will be described. Thepairing list may be managed and stored in a unified manner by anyapparatus included in the image transmitting/receiving system 1, ofmanaged and stored by each apparatus. In addition, when each apparatusmanages and stores the pairing list, all pairing lists need to have thesame information.

FIG. 6 is a schematic diagram representing an example of the pairinglist in accordance with the present preferred embodiment. In theillustrated example, the pairing list has data items of “ID,” “Tx ID,”“CH ID,” “Rx ID,” and “Sync,” and stores data of each data item byassociating the data in each row.

The data item “ID” stores a number for uniquely specifying a set of datastored in the pairing list. The data item “Tx ID” stores a number foruniquely specifying an image transmitting apparatus 10. The data item“CH ID” stores a number for uniquely specifying a channel used inwireless communication between an image transmitting apparatus 10uniquely specified by “Tx ID” stored in the same row and a receivedimage displaying apparatus 20 uniquely specified by “Rx ID” stored inthe same row. The data item “Rx ID” stores a number for uniquelyspecifying a received image displaying apparatus 20. The data item“Sync” stores information indicating a communication state between theimage transmitting apparatus 10 uniquely specified by the “Tx ID” storedin the same row and the received image displaying apparatus 20 uniquelyspecified by the “Rx ID” stored in the same row. In addition, when the“Sync” is “OK,” it indicates that synchronous transmission is beingperformed. When the “Sync” is “None,” it indicates a non-connection.When the “Sync” is “During,” it indicates that synchronization is beingset (a connection is currently not possible).

In the illustrated example, a value stored in the data item “ID” of arow 601 is “001,” a value stored in the data item “Tx ID” is “0001,” avalue stored in the data item “CH ID” is “001,” a value stored in thedata item “Rx ID” is “000.1,” and a value stored in the data item “Sync”is “OK.” Accordingly, a set of data specified by the ID “001” indicatesthat an image transmitting apparatus 10 uniquely specified by the Tx ID“0001” and a received image displaying apparatus 20 uniquely specifiedby the Rx ID “0001” are connected to each other for communication usinga channel specified by the CH ID “001,” and indicates that synchronoustransmission is being performed because the Sync is “OK.” Other rows areas illustrated in FIG. 6.

In addition, FIG. 7 illustrates an example of a pairing list when acommunication destination of a received image displaying apparatus 20uniquely specified by the Tx ID “0003” and a received image displayingapparatus 20 uniquely specified by the Tx ID “0004” has changed in thestate of the pairing list illustrated in FIG. 6. In the illustratedexample, sets of data uniquely specified by the IDs “003” to “005” aredifferent from the example illustrated in FIG. 6. In this way; when aconnection state between the image transmitting apparatus 10 and thereceived image displaying apparatus 20 changes, the pairing list is alsoupdated. In addition, the content indicated by each row is asillustrated in FIG. 7.

Next, an update process of the pairing list will be described. As anexample, the case in which, when the image transmitting apparatus 10-2transmits the reference synchronization signal and manages theconsistency of the pairing list, a connection destination of the imagetransmitting apparatus 10-2 and the image transmitting apparatus 10-3has changed will be described.

When disconnection and connection processes are generated due to achange in the connection destination, the image transmitting apparatuses10-2 and 10-3 update pairing lists stored therein. Then, the imagetransmitting apparatus 10-3, which transmits no referencesynchronization signal, transmits update content of the pairing list tothe image transmitting apparatus 10-2. The image transmitting apparatus10-2 having received the update content updates the pairing list storedtherein based on the received content, and transmits an updated pairinglist to all the image transmitting apparatuses 10 included in the imagetransmitting/receiving system 1. The image transmitting apparatuses 10having received the pairing first update pairing lists stored thereinbased on the received content.

As described above, since the image transmitting apparatus 10-2 managingthe consistency of the pairing list is notified of updated content whena communication connection environment of another image transmittingapparatus 10 (or another received image displaying apparatus 20) hasbeen updated as well as when a communication connection environment ofthe image transmitting apparatus 10-2 has been updated, the imagetransmitting apparatus 10-2 is able to update the pairing list storedtherein. Furthermore, after updating the pairing list, the imagetransmitting apparatus 10-2 transmits the updated pairing list to allthe image transmitting apparatuses if) included in the imagetransmitting/receiving system 1. In this way, it is possible to maintainthe consistency of the pairing lists stored in the image transmittingapparatuses 10 included in the image transmitting/receiving system 1. Inaddition, since the update process of the pairing list is performedwithin the blanking interval (in addition, it may not be a blankinginterval when the connection environment has been updated), it ispossible to perform the process without influencing thetransmission/reception of an image signal.

In addition, in order to share the pairing list, the pairing list may bebroadcast or multicast to each channel at a predetermined timing duringthe blanking interval, in this way, the image transmitting apparatuses10 and the received image displaying apparatuses 20 included in theimage transmitting/receiving system 1 are able to receive the pairinglist. Furthermore, the predetermined timing is arbitrary. For example,the pairing list is transmitted at a timing of once per second (onceevery 60 frames in the case of a moving image of 60 frames).Furthermore, the pairing list may also be transmitted in a multicastmanner.

Each apparatus included in the image transmitting/receiving system 1 isable to share the pairing list, and an image transmitting apparatus 10and a received image displaying apparatus 20, which newly perform aconnection operation, are able to select a device with which theblanking interval synchronizes. In this way, it is possible totransmit/receive a control signal out of the transmission/receptiontimings of a moving image, so that it is possible to prevent a collisionwith the transmission/reception of the moving image.

Next, an operation procedure of the image transmitting apparatus 10 willbe described. FIG. 8 is a flowchart illustrating the operation procedureof the image transmitting apparatus 10 in accordance with the presentpreferred embodiment.

(Step S101) The terminal detection unit 160 searches for anotherapparatus included in the image transmitting/receiving system 1. Then,the procedure proceeds to a process of step S102.

(Step S102) The recognition unit 151 determines whether a referencesynchronization signal transmitted from another apparatus has beenreceived in the reception unit 182 during a constant period. When therecognition unit 151 determines that the reference synchronizationsignal transmitted from another apparatus has been received in thereception unit 182, the procedure proceeds to a process of step S103.Otherwise, the procedure proceeds to a process of step S109.

(Step S103) The communication control unit 170 matches a receptionchannel of the reception unit 182 with a channel through which thereference synchronization signal has been transmitted in order toreceive the reference synchronization signal. Then, the procedureproceeds to a process of step S104.

(Step S104) The reception unit 182 receives the referencesynchronization signal transmitted from another image transmittingapparatus 10. Furthermore, the recognition unit 151 recognizes a timingat which an image signal is transmitted, and a timing of a blankinginterval based on the reference synchronization signal received in thereception unit 182. Then, the procedure proceeds to a process of stepS105.

(Step S105) The communication control unit 170 changes a channel throughwhich the transmission unit 181 transmits an image signal (an imagesignal packet) to a free channel. Then, the procedure proceeds to aprocess of step S106.

(Step S106) The transmission unit 181 performs a communicationconnection with the received image displaying apparatus 20, which is acommunication partner determined in advance, using the channel set inthe process of step S105. Then, the procedure proceeds to a process ofstep S107.

(Step S107) The image signal generation unit 130 generates an imagesignal of one frame using the moving image data stored in the imageholding unit 121. Then, the procedure proceeds to a process of stepS108.

(Step S108) The communication control unit 170 allows the image signalof one frame generated by the image signal generation unit 130 in theprocess of step S107 to synchronize with the timing at which the imagesignal is transmitted, which has been recognized by the recognition unit151 in the process of step S104, and transmits the image signal to thereceived image displaying apparatus 20 having performed thecommunication connection in the process of step S106. Then, theprocedure returns to the process of step S107. In addition, the imagesignal generation unit 130 and the communication control unit 170 repeatthe processes of step S107 and step S108 until the transmission of theimage signal is stopped, such as the reception of a transmission stopinstruction by the instruction input unit 190.

(Step S109) When the reference synchronization signal has not beenreceived in step S102, the control unit 150 controls the referencesynchronization signal generation unit 140 to generate the referencesynchronization signal. The reference synchronization signal generationunit 140 generates the reference synchronization signal. In addition,the reference synchronization signal generation unit 140 continuouslygenerates the reference synchronization signal until the imagetransmitting apparatus 10 is powered off. Then, the procedure proceedsto a process of step S110.

(Step S110) The transmission unit 181 performs a communicationconnection with the received image displaying apparatus 20, which is acommunication partner determined in advance, using a currently setchannel. Then, the procedure proceeds to a process of step S111.

(Step S111) The image signal generation unit 130 generates the imagesignal of one frame using the moving image data stored in the imageholding unit 121. Then, the procedure proceeds to a process of stepS112.

(Step S112) The communication control unit 170 controls the transmissionunit 181 to transmit the image signal of one frame generated by theimage signal generation unit 130 in the process of step S111 to thereceived image displaying apparatus 20 having performed thecommunication connection in the process of step S110. Then, theprocedure proceeds to a process of step S113.

(Step S113) The recognition unit 151 recognizes whether a current timepoint is a blanking interval based on the reference synchronizationsignal generated by the reference synchronization signal generation unit140 in the process of step S109. When the recognition unit 151recognizes that the current time point is the blanking interval theprocedure proceeds to a process of step S114. Otherwise, the procedurereturns to the process of step S111.

(Step S114) Since the current time point is the blanking interval, thecommunication control unit 170 controls the transmission unit 181 totransmit the reference synchronization signal generated by the referencesynchronization signal generation unit 140 to other image transmittingapparatuses 10 included in the image transmitting/receiving system 1 inthe form of a packet. Then, the procedure proceeds to a process of stepS115.

(Step S115) The communication control unit 170 temporarily stops (waitsfor) a transmission process until the blanking interval ends. After theblanking interval ends, the procedure returns to the process of stepS111.

In the case in which the aforementioned processes of step S101 to stepS115 are performed, when another apparatus transmits no referencesynchronization signal, the image transmitting apparatus 10 is able togenerate the reference synchronization signal and transmit the generatedreference synchronization signal to other apparatuses in the blankinginterval. Furthermore, based on the reference synchronization signal,the oilier apparatuses having received the reference synchronizationsignal are able to recognize the image signal transmission timing andthe blanking interval.

FIG. 9 is a schematic diagram representing image signal transmissiontimings and blanking intervals in accordance with the present preferredembodiment. In addition, a horizontal axis denotes time. In theillustrated example, the image transmitting apparatus 10-1 and thereceived image displaying apparatus 20-1 perform thetransmission/reception of an image signal and the image transmittingapparatus 10-2 and the received image displaying apparatus 20-2 performthe transmission/reception of an image signal. Since the imagetransmitting apparatus 10-1 and the image transmitting apparatus 10-2transmit the image signal based on the reference synchronization signal,the timing at which the image transmitting apparatus 10-1 transmits theimage signal coincides with the timing at which the image transmittingapparatus 10-2 transmits the image signal. Furthermore, the blankingintervals in the image transmitting apparatus 10-1 and the imagetransmitting apparatus 10-2 coincide with each other. In addition, allthe apparatuses included in the image transmitting/receiving system 1perform the transmission/reception of the image signal at theillustrated timings at which the image signal is transmitted and at theillustrated timings at which the blanking intervals coincide with eachother.

Next, a detailed example when switching a connection between the imagetransmitting apparatus 10 and the received image displaying apparatus 20will be described. FIG. 10 is a sequence diagram representing anoperation procedure when switching a connection between the imagetransmitting apparatus 10 and the received image displaying apparatus 20in accordance with the present preferred embodiment. A vertical axisindicates the passage of time. FIG. 10 illustrates an example of thecase in which, when the image transmitting apparatus 10-2 transmits animage signal to the received image displaying apparatuses 20-2 and 20-3using a communication channel CH2, and the image transmitting apparatus10-3 transmits an image signal to the received image displayingapparatus 20-4 using a communication channel CH3, a destination to whichthe image transmitting apparatus 10-3 transmits the image signal isswitched to the received image displaying apparatus 20-3.

(Step S201) The image transmitting apparatus 10-2 transmits an imagesignal to the received image displaying apparatuses 20-2 and 20-3, andthe image transmitting apparatus 10-3 transmits an image signal to thereceived image displaying apparatus 20-4. The image transmittingapparatus 10-2 and the image transmitting apparatus 10-3 transmit theimage signals according to the image signal transmission timing based onthe reference signal as described above. In addition, in FIG. 10, thetiming at which the image transmitting apparatus 10-2 transmits theimage signal to the received image displaying apparatuses 20-2 and 20-3is different from the timing at which the image transmitting apparatus10-3 transmits the image signal to the received image displayingapparatus 20-4. However, this is for illustrative purposes only, and theimage transmitting apparatus 10-2 and the image transmitting apparatus10-3 actually transmit the image signals at the same timing.

(Step S202) The instruction input unit 190 of the image transmittingapparatus 10-3 receives the input of an instruction for switching atransmission destination of the image signal from the received imagedisplaying apparatus 20-4 to the received image displaying apparatus20-3.

(Step S203) The image transmitting apparatus 10-3 switches acommunication channel from the CH3 to the CH2.

(Step S204) After a blanking interval starts, the image transmittingapparatus 10-3 transmits a switching request message for asking forpermission to start communication with the received image displayingapparatus 20-4 to the image transmitting apparatus 10-2.

(Step S205) When the switching request message is received in theprocess of step S203, the image transmitting apparatus 10-2 determineswhether to permit the communication with the received image displayingapparatus 20-4, and transmits a switching permission message to theimage transmitting apparatus 10-3 when it is determined to permit thecommunication.

(Step S206) The image transmitting apparatuses 10-2 and 10-3 determinewhether it is possible to switch a communication connection within theblanking interval. When it is determined that it is possible to switchthe communication connection within the blanking interval, the imagetransmitting apparatuses 10-2 and 10-3 perform processes after stepS206. When it is determined that it is not possible to switch thecommunication connection within the blanking interval, the imagetransmitting apparatuses 10-2 and 10-3 return the CH to the originalchannel stop a switching process of the communication connection in thisblanking interval, and perform the processes after step S206 in the nextblanking interval.

(Step S207) The image transmitting apparatus 10-3 transmits a connectionrequest message to the received image displaying apparatus 20-3.

(Step S208) The received image displaying apparatus 20-3 transmits adisconnection request message to the image transmitting apparatus 10-2.

(Step S209) The image transmitting apparatus 10-2 transmits adisconnection message to the received image displaying apparatus 20-3,and then disconnects a communication connection with the received imagedisplaying apparatus 20-3.

(Step S210) The received image displaying apparatus 20-3 disconnects acommunication connection with the image transmitting apparatus 10-2, andthen transmits a disconnection completion message to the imagetransmitting apparatus 10-3.

(Step S211) The image transmitting apparatus 10-3 and the received imagedisplaying apparatus 20-3 switch a communication channel from the CH2 tothe CH3.

(Step S212) The image transmitting apparatus 10-3 transmits adisconnection request message to the received image displaying apparatus20-4.

(Step S213) The received image displaying apparatus 20-4 transmits adisconnection completion message and information specifying a channel (afree channel) to be used later by the received image displayingapparatus 20-4 to the image transmitting apparatus 10-3, and thendisconnects a communication connection with the image transmittingapparatus 10-3. Then, the received image displaying apparatus 20-4changes a communication channel to the free channel and waits for aconnection.

(Step S214) The image transmitting apparatus 10-2 deletes the receivedimage displaying apparatus 20-3 from the pairing list stored therein,and updates the pairing list.

(Step S215) The image transmitting apparatus 10-2 deletes a combinationwith the received image displaying apparatus 20-4 from the pairing liststored therein, and updates a communication channel which is stored inthe pairing list and used by the received image displaying apparatus20-4, based on the information received in the process of step S213 andspecifying the channel to be used later by the received image displayingapparatus 20-4.

(Step S216) The image transmitting apparatus 10-3 switches acommunication channel from the CH3 to the CH2.

(Step S217) The image transmitting apparatus 10-3 transmits the pairinglist updated in the process of step S215 to the image transmittingapparatus 10-2.

(Step S218) The image transmitting apparatus 10-2 updates the pairinglist stored therein based on the pairing list received in the process ofstep S217.

(Step S219) The image transmitting apparatus 10-2 transmits the pairinglist updated in the process of step S218 to the image transmittingapparatus 10-3. The image transmitting apparatus 10-3 updates thepairing list stored therein based on the received pairing list.

(Step S220) The image transmitting apparatus 10-3 switches acommunication channel from the CH2 to the CH3.

(Step S221) The image transmitting apparatus 10-3 starts a communicationconnection with the received image displaying apparatus 20-3, and thentransmits a connection message to the received image displayingapparatus 20-3.

(Step S222) The received image displaying apparatus 20-3 starts acommunication connection with the image transmitting apparatus 10-3, andthen transmits a connection completion message to the image transmittingapparatus 10-3.

(Step S223) The image transmitting apparatus 10-2 and the imagetransmitting apparatus 10-3 perform update processes (which are the sameas the processes of step S214 to step S220) of the pairing lists.

(Step S224) After the blanking interval ends, the image transmittingapparatus 10-2 transmits the image signal to the received imagedisplaying apparatus 20-2, and the image transmitting apparatus 10-3transmits the image signal to the received image displaying apparatus20-3. In addition, in FIG. 10, the timing at which the imagetransmitting apparatus 10-2 transmits the image signal to the receivedimage displaying apparatus 20-2 is different from the timing at whichthe image transmitting apparatus 10-3 transmits the image signal to thereceived image displaying apparatus 20-3. However, this is forillustrative purposes only, and the image transmitting apparatus 10-2and the image transmitting apparatus 10-3 actually transmit the imagesignals at the same timing.

In addition, in the aforementioned example, the list update processes(the processes of step S214 to step S220 and the process of step S223)are performed in the blanking interval when the communication switchingprocess has been performed. However, the present invention is notlimited thereto. For example, the list update processes may be performedin the blanking interval after that in which the communication switchingprocess has been performed.

As with the aforementioned processes of step S201 to step S224, whenswitching a connection destination apparatus, the image transmittingapparatuses 10 and the received image displaying apparatuses 20 includedin the image transmitting/receiving system 1 perform thetransmission/reception of data required in order to switch theconnection destination apparatus during the blanking interval.Consequently, it is possible to perform the switching of a communicationconnection without influencing the transmission/reception of an imagesignal.

As described above, according to the present preferred embodiment, oneof the image transmitting apparatuses 10 included in the imagetransmitting/receiving system 1 transmits the reference synchronizationsignal indicating the transmission timing of the image signal to theother image transmitting apparatuses 10. Then, all the imagetransmitting apparatuses 10 included in the image transmitting/receivingsystem 1 transmit the image signal based on the referencesynchronization signal. In this way, all the image transmittingapparatuses 10 included in the image transmitting/receiving system 1 areable to allow the timing at which the image signal is transmitted tosynchronize with the timing (the blanking interval) at which the imagesignal is not transmitted. Furthermore, when switching a connectiondestination apparatus, the image transmitting apparatuses 10 and thereceived image displaying apparatuses 20 included in the imagetransmitting/receiving system 1 perform the transmission/reception ofdata required in order to switch the connection destination apparatusduring the blanking interval. Consequently, it is possible to performthe switching of a communication connection without influencing thetransmission/reception of an image signal.

Second Preferred Embodiment

Next, a second preferred embodiment of the present invention will bedescribed. A difference between the present preferred embodiment and thefirst preferred embodiment is that the reference synchronization signalis transmitted to all channels in the present preferred embodiment. Inaddition, an image transmitting/receiving system 1, an imagetransmitting apparatus 10, and a received image displaying apparatus 20have the same configurations as those of the imagetransmitting/receiving system 1, the image transmitting apparatus 10,and the received image displaying apparatus 20 of the first preferredembodiment.

Next, an operation procedure of the image transmitting apparatus 10 willbe described. FIG. 11 is a flowchart illustrating the operationprocedure of the image transmitting apparatus 10 in accordance with thepresent preferred embodiment.

Processes of step S30.1 to step S313 are the same as the processes ofstep S101 to step S113 in the first preferred embodiment.

(Step S314) The control unit 150 determines whether there is a channelthrough which the reference synchronization signal is not transmitted.When the control unit 150 determines that there is a channel throughwhich the reference synchronization signal is not transmitted, theprocedure proceeds to a process of step S315. When the control unit 150determines that there is no channel through which the referencesynchronization signal is not transmitted, the procedure returns to theprocess of step S311.

(Step S315) The communication control unit 170 changes a communicationchannel of the transmission unit 181 to the channel through which thereference synchronization signal is not transmitted. Then, the procedureproceeds to a process of step S316.

(Step S316) The communication control unit 170 controls the transmissionunit 181 to transmit the reference synchronization signal generated bythe reference synchronization signal generation unit 140 in the form ofa packet using the channel set in the process of step S315. Then, theprocedure proceeds to a process of step S317.

(Step S317) The control unit 150 determines whether the referencesynchronization signal has been transmitted to all channels. When thecontrol unit 150 determines that the reference synchronization signalhas been transmitted to all the channels, the procedure proceeds to aprocess of step S321. Otherwise, the procedure proceeds to the processof step S318.

(Step S318) The recognition unit 151 recognizes whether the blankinginterval has ended based on the reference synchronization signalgenerated by the reference synchronization signal generation unit 140 inthe process of step S309. When the recognition unit 151 recognizes thatthe blanking interval has ended, the procedure proceeds to a process ofstep S320. Otherwise, the procedure proceeds to the process of stepS319.

(Step S319) The communication control unit 170 changes the communicationchannel of the transmission unit 181 to the channel through which thereference synchronization signal is not transmitted. Then, the procedurereturns to the process of step S316.

(Step S320) The control unit 150 allows the channel through which thereference synchronization signal is not transmitted to be stored in thestorage unit 120. Then, the procedure proceeds to a process of stepS321.

(Step S321) The communication control unit 170 returns the communicationchannel of the transmission unit 181 to the original channel. Then, theprocedure proceeds to a process of step S322.

(Step S322) The communication control unit 170 waits for (temporarilystops) a process until the blanking interval ends. After the blankinginterval ends, the procedure returns to the process of step S311.

As described above, according to the present preferred embodiment, oneof the image transmitting apparatuses 10 included in the imagetransmitting/receiving system 1 is able to transmit the referencesynchronization signal to all the channels within the blanking interval,in addition, instead of transmitting the reference synchronizationsignal to all the channels within a single blanking interval, it may bepossible to transmit the reference synchronization signal to all thechannels over a plurality of blanking intervals or to transmit tirereference synchronization signal only to one channel within the singleblanking interval.

Third Preferred Embodiment

Next, a third preferred embodiment of the present invention will bedescribed. A difference between the present preferred embodiment and thefirst preferred embodiment is that a received image displaying apparatus20 generates and transmits the reference synchronization signal in thepresent preferred embodiment. In addition, an imagetransmitting/receiving system 1, an image transmitting apparatus 10, andthe received image displaying apparatus 20 have the same configurationsas those of the image transmitting/receiving system 1, the imagetransmitting apparatus 10, and the received image displaying apparatus20 of the first preferred embodiment.

Next, a data structure of the reference synchronization signal isdescribed. FIG. 12 is a schematic diagram representing the datastructure of the reference synchronization signal in accordance with thepresent preferred embodiment. In the illustrated example, the referencesynchronization signal has data items of a header BlankSync, adestination address, a transmission source address, t_ack, and an FCS(Frame Check Sequence). The header, the destination address, thetransmission source address, and the FCS are the same data items as thedata items of the first preferred embodiment. As the t_ack, a periodt_ack indicating a period until a blanking interval ends is stored.

Next, details of timings at which the communication control unit 310 ofthe received image displaying apparatus 20 transmits the referencesynchronization signal will be described. FIG. 13 is a schematic diagramrepresenting timings at which the communication control unit 310transmits the reference synchronization signal in accordance with thepresent preferred embodiment. In addition, a horizontal axis denotestime.

As illustrated in FIG. 13, the communication control unit 310 transmitsan ACK signal for a final packet of an image signal frame to the imagetransmitting apparatus 10, and then transmits the referencesynchronization signal. In addition, according to a method fordetermining the final packet of the image signal frame, for example,when data amounts of frames received in the received image displayingapparatus 20 are accumulated and reach an image data amount of oneframe, it is determined as the final packet of the image signal.

In addition, as described above, the reference synchronization signalincludes the period t_ack until the blanking interval ends. Thus, theimage transmitting apparatus 10 having received the referencesynchronization signal starts to transmit an image signal frame afterthe passage of the period t_ack until the blanking interval ends, sothat it is possible to achieve synchronization of blank intervals andimage signal transmission timings among all the image transmittingapparatuses 10 included in the image transmitting/receiving system 1.

Next, an operation procedure of the received image displaying apparatus20 will be described. FIG. 14 is a flowchart illustrating the operationprocedure of the received image displaying apparatus 20 in accordancewith the present preferred embodiment.

(Step S401) The terminal detection unit 340 searches for anotherapparatus included in the image transmitting/receiving system 1. Then,the procedure proceeds to a process of step S402.

(Step S402) The recognition unit 321 determines whether a referencesynchronization signal transmitted from another apparatus has beenreceived in the reception unit 302 during a constant period. When therecognition unit 321 determines that the reference synchronizationsignal transmitted from another apparatus has been received in thereception unit 302, the procedure proceeds to a process of step S403.Otherwise, the procedure proceeds to a process of step S407.

(Step S403) The communication control unit 310 waits until an imagetransmitting apparatuses 10 is connected. When the image transmittingapparatuses 10 is connected, the procedure proceeds to a process of stepS404.

(Step S404) The reception unit 302 performs a communication connectionwith the image transmitting apparatuses 10 connected in the process ofstep S403. Then, the procedure proceeds to a process of step S405.

(Step S405) The reception unit 302 receives an image signal transmittedfrom the image transmitting apparatuses 10 for which the communicationconnection has been performed in the process of step S404. Then, theprocedure proceeds to a process of step S406.

(Step S406) The display unit 370 displays a moving image based on theimage signal received in the reception unit 302 in the process of stepS405. Then, the procedure returns to the process of step S405. Inaddition, the reception unit 302 and the display unit 370 repeat theprocesses of step S405 and step S406 until the reception of the imagesignal is stopped, such as the reception of a reception stop instructionby the instruction input unit 190.

(Step S407) The control unit 320 allows the reference synchronizationsignal generation unit 330 to generate the reference synchronizationsignal. The reference synchronization signal generation unit 330generates the reference synchronization signal. In addition, thereference synchronization signal generation unit 330 continuouslygenerates the reference synchronization signal until the received imagedisplaying apparatus 20 is powered off. Then, the procedure proceeds toa process of step 408.

(Step S408) The communication control unit 310 waits until an imagetransmitting apparatus 10 is connected. When the image transmittingapparatus 10 is connected, the procedure proceeds to a process of stepS409.

(Step S409) The reception unit 302 performs a communication connectionwith the image transmitting apparatus 10 connected in the process ofstep S408. Then, the procedure proceeds to a process of step S410.

(Step S410) The reception unit 302 receives a frame of an image signaltransmitted from the image transmitting apparatus 10 for which thecommunication connection has been performed in the process of step S409.Then, the procedure proceeds to a process of step S411.

(Step S411) The transmission unit 301 transmits ACK. Then, the procedureproceeds to a process of step 412

(Step S412) The recognition unit 321 recognizes whether the frame of theimage signal received in the reception unit 302 in the process of stepS410 is a frame immediately before a blanking interval. When therecognition unit 321 recognizes that the frame received in the receptionunit 302 in the process of step S410 is the frame immediately before theblanking interval, the procedure proceeds to a process of step S413.Otherwise, the procedure returns to the process of step S410.

(Step S413) The communication control unit 310 controls the transmissionunit 301 to transmit the reference synchronization signal generated bythe reference synchronization signal generation unit 330 to other imagetransmitting apparatuses 10 and other received image displayingapparatuses 20 included in the image transmitting/receiving system 1 inthe form of a packet. Then, the procedure returns to the process of stepS410.

In the case in which the aforementioned processes of step S401 to stepS413 are performed, when another apparatus transmits no referencesynchronization signal, the received image displaying apparatus 20 isable to generate the reference synchronization signal and transmit thegenerated reference synchronization signal to other apparatuses in theblanking interval. Furthermore, the other apparatuses having receivedthe reference synchronization signal are able to recognize the imagesignal transmission timing and the blanking interval based on thereference synchronization signal.

Next, a detailed example when switching a connection between the imagetransmitting apparatus 10 and the received image displaying apparatus 20will be described. FIG. 15 is a sequence diagram representing anoperation procedure when switching a connection between the imagetransmitting apparatus 10 and the received image displaying apparatus 20in accordance with the present preferred embodiment. A vertical axisindicates the passage of time. FIG. 15 illustrates a detailed example ofthe case in which, when the image transmitting apparatus 10-2 transmitsan image signal to the received image displaying apparatuses 20-2 and20-3 using a communication channel CH2, and the image transmittingapparatus 10-3 transmits an image signal to the received imagedisplaying apparatus 20-4 using a communication channel CH3, adestination from which the received image displaying apparatus 20-3receives the image signal is switched to the image transmittingapparatus 10-3.

(Step S501) The image transmitting apparatus 10-2 transmits an imagesignal to the received image displaying apparatuses 20-2 and 20-3, andthe image transmitting apparatus 10-3 transmits an image signal to thereceived image displaying apparatus 20-4. The image transmittingapparatus 10-2 and the image transmitting apparatus 10-3 transmit tireimage signals according to the image signal transmission timing based onthe reference signal as described above. In addition, in FIG. 15, thetiming at which the image transmitting apparatus 10-2 transmits theimage signal to the received image displaying apparatuses 20-2 and 20-3is different from the timing at which the image transmitting apparatus10-3 transmits the image signal to the received image displayingapparatus 20-4. However, this is for illustrative purposes only, and theimage transmitting apparatus 10-2 and the image transmitting apparatus10-3 actually transmit the image signals at tire same timing.

(Step S502) The instruction input unit 360 of the received imagedisplaying apparatus 20-3 receives the input of an instruction forswitching a reception destination of the image signal from the imagetransmitting apparatus 10-2 to the image transmitting apparatus 10-3.

(Step S503) After a blanking interval starts, the received imagedisplaying apparatus 20-3 transmits a switching confirmation message forasking permission to start communication with the image transmittingapparatus 10-3 to the image transmitting apparatus 10-2.

(Step S504) When the switching confirmation message is received, in theprocess of step S503, the image transmitting apparatus 10-2 determineswhether to permit the communication with the image transmittingapparatus 10-3, and transmits a switching permission message to thereceived image displaying apparatus 20-3 when it is determined to permitthe communication.

(Step S505) The received image displaying apparatus 20-3 transmits adisconnection request message to the image transmitting apparatus 10-2.

(Step S506) The image transmitting apparatus 10-2 transmits adisconnection completion message to the received image displayingapparatus 20-3, and then disconnects a communication connection with thereceived image displaying apparatus 20-3.

(Step S507) The received image displaying apparatus 20-3 disconnects acommunication connection with the image transmitting apparatus 10-2, andthen switches a communication channel from the CH2 to the CH3.

(Step S508) The received image displaying apparatus 20-3 transmits adisconnection request message to the received image displaying apparatus20-4.

(Step S509) The received image displaying apparatus 20-4 transmits adisconnection instruction message to the image transmitting apparatus10-3, and then disconnects a communication connection with the imagetransmitting apparatus 10-3.

(Step S510) The received image displaying apparatus 20-4 transmits adisconnection completion message and information specifying a channel (afree channel) to be used later by the received image displayingapparatus 20-4 to the received image displaying apparatus 20-3, and thendisconnects a communication connection with the image transmittingapparatus 10-3. Then, the received image displaying apparatus 20-4changes a communication channel to the free channel.

(Step S511) The received image displaying apparatus 20-3 transmits aconnection request message to the image transmitting apparatus 10-3.

(Step S512) After starting a communication connection with the receivedimage displaying apparatus 20-3, the image transmitting apparatus 10-3transmits a connection completion message to the received imagedisplaying apparatus 20-3.

(Step S513) The image transmitting apparatuses 10-2 and 10-3 and thereceived image displaying apparatuses 20-1, 20-2, and 20-3 performupdate processes of pairing lists. In addition, the update processes ofthe pairing lists are the same as the update processes of the pairinglists in the first preferred embodiment.

(Step S514) The received image displaying apparatus 20-4 waits for aconnection.

(Step S515) After the blanking interval ends, the image transmittingapparatus 10-2 transmits the image signal to the received imagedisplaying apparatus 20-2, and the image transmitting apparatus 10-3transmits the image signal to the received image displaying apparatus20-3. In addition, in FIG. 15, the timing at which the imagetransmitting apparatus 10-2 transmits the image signal to the receivedimage displaying apparatus 20-2 is different from the timing at whichthe image transmitting apparatus 10-3 transmits the image signal to thereceived image displaying apparatus 20-3. However, this is forillustrative purposes only, and the image transmitting apparatus 10-2and the image transmitting apparatus 10-3 actually transmit the imagesignals at the same timing.

As with the aforementioned processes of step S501 to step S515, whenswitching a connection destination apparatus, the image transmittingapparatuses 10 and the received image displaying apparatuses 20 includedin the image transmitting/receiving system 1 perform thetransmission/reception of data required in order to switch theconnection destination apparatus during the blanking interval.Consequently, it is possible to perform the switching of a communicationconnection without influencing the transmission/reception of an imagesignal.

As described above, according to the present preferred embodiment, oneof the received image displaying apparatuses 20 included in the imagetransmitting/receiving system 1 transmits the reference synchronizationsignal indicating the transmission timing of the image signal to theother received image displaying apparatuses 20 and the other imagetransmitting apparatuses 10. Then, all the image transmittingapparatuses 10 included in the image transmitting/receiving system 1transmit the image signal based on the reference synchronization signal.In this way, all the image transmitting apparatuses 10 included in theimage transmitting/receiving system 1 are able to allow the timing atwhich the image signal is transmitted to synchronize with the timing(the blanking interval) at which the image signal is not transmitted.Furthermore, when switching a connection destination apparatus, theimage transmitting apparatuses 10 and the received image displayingapparatuses 20 included in the image transmitting/receiving system 1perform the transmission/reception of data required in order to switchthe connection destination apparatus during the blanking interval.Consequently, it is possible to perform the switching of a communicationconnection without influencing the transmission/reception of an imagesignal.

Fourth Preferred Embodiment

Next, a fourth preferred embodiment of the present invention will bedescribed. A difference between the present preferred embodiment and thethird preferred embodiment is that the reference synchronization signalis transmitted to all channels in the present preferred embodiment. Inaddition, an image transmitting/receiving system 1, an imagetransmitting apparatus 10, and a received image displaying apparatus 20have the same configurations as those of the imagetransmitting/receiving system 1, the image transmitting apparatus 10,and the received image displaying apparatus 20 of the third preferredembodiment.

Next, an operation procedure of the received image displaying apparatus20 will be described. FIG. 16 is a flowchart illustrating the operationprocedure of the image transmitting apparatus 10 in accordance with thepresent preferred embodiment.

Processes of step S601 to step S6.12 are the same as the processes ofstep S401 to step S412 in the third preferred embodiment.

(Step S613) The control unit 320 determines whether there is a channelthrough which the reference synchronization signal is not transmitted.When the control unit 320 determines that there is a channel throughwhich the reference synchronization signal is not transmitted, theprocedure proceeds to a process of step S6.14. When the control unit 320determines that there is no channel through which the referencesynchronization signal is not transmitted, the procedure returns to theprocess of step S6.10.

(Step S614) The communication control unit 310 changes a communicationchannel of the transmission unit 301 to the channel through which thereference synchronization signal is not transmitted. Then, the procedureproceeds to a process of step S615.

(Step S615) The communication control unit 310 controls the transmissionunit 301 to transmit the reference synchronization signal generated bythe reference synchronization signal generation unit 330 in the form ofa packet using the channel set in the process of step S614. Then, theprocedure proceeds to a process of step S616.

(Step S616) The control unit 320 determines whether the referencesynchronization signal has been transmitted to all channels. When thecontrol unit 320 determines that the reference synchronization signalhas been transmitted to all the channels, the procedure proceeds to aprocess of step S620. Otherwise, the procedure proceeds to a process ofstep S617.

(Step S617) The recognition unit 321 recognizes whether the blankinginterval has ended based on the reference synchronization signalgenerated by the reference synchronization signal generation unit 330.When the recognition unit 321 recognizes that the blanking interval hasended, the procedure proceeds to a process of step S619. Otherwise, theprocedure proceeds to a process of step S618.

(Step S618) The communication control unit 310 changes the communicationchannel of the transmission unit 301 to the channel through which thereference synchronization signal is not transmitted. Then, the procedurereturns to the process of step S615.

(Step S619) The control unit 320 allows the channel through which thereference synchronization signal is not transmitted to be stored in thestorage unit 350. Then, the procedure proceeds to a process of stepS620.

(Step S620) The communication control unit 310 returns die communicationchannel of the transmission unit 301 to the original channel. Then, theprocedure returns to the process of step S610.

As described above, according to the present preferred embodiment, oneof the received image displaying apparatuses 20 included in the imagetransmitting/receiving system 1 is able to transmit the referencesynchronization signal to all the channels within the blanking interval.In addition, instead of transmitting the reference synchronizationsignal to all the channels within a single blanking interval, it may bepossible to transmit the reference synchronization signal to all thechannels over a plurality of blanking intervals or to transmit thereference synchronization signal only to one channel within the singleblanking interval.

Fifth Preferred Embodiment

Next, a fifth preferred embodiment of the present invention will bedescribed with reference to the accompanying drawings. FIG. 17 is aschematic diagram representing the configuration of an imagetransmitting/receiving system in accordance with the present preferredembodiment. In the illustrated example, an image transmitting/receivingsystem 2 includes image transmitting apparatuses 10-1 to 10-3, receivedimage displaying apparatuses 20-1 to 20-4, and a remote controlapparatus 30. In addition, the image transmitting apparatus 10 and thereceived image displaying apparatus 20 have the same configurations asthose of the image transmitting apparatus 10 and the received imagedisplaying apparatus 20 of the first preferred embodiment. The remotecontrol apparatus 30 receives the input of an instruction from a user,and transmits an instruction to other apparatuses included in the imagetransmitting/receiving system 2 based on the received instruction.

Next, the configuration of the remote control apparatus 30 will bedescribed. FIG. 18 is a block diagram representing the configuration ofthe remote control apparatus 30 in accordance with the present preferredembodiment. In the illustrated example, the remote control apparatus 30includes a storage unit 510, a reference synchronization signalgeneration unit 520, a control unit 530, a terminal detection unit 540,a communication control unit 550, a wireless unit 560 (a wirelesscommunication unit), an instruction input unit 570, and a display unit580.

The storage unit 510 includes a list management unit 511. The listmanagement unit 511 stores a pairing list indicating combinations of theimage transmitting apparatuses 10 and the received image displayingapparatuses 20, which perform communication. The referencesynchronization signal generation unit 520 generates a referencesynchronization signal indicating a transmission timing of an imagesignal in all the image transmitting apparatuses 10 included in theimage transmitting/receiving system 2. The control unit 530 performs thecontrol of each element provided in the remote control apparatus 30.Furthermore, the control unit 530 includes a recognition unit 531 thatrecognizes a timing at which an image signal is transmitted, and ablanking interval, which indicates a timing at which control data istransmitted, based on the reference synchronization signal.

The terminal detection unit 540 searches for another apparatus includedin the image transmitting/receiving system 2. The communication controlunit 550 performs the communication control (a baseband process). Thewireless unit 560 includes a transmission unit 561 and a reception unit562. The transmission, unit 561 wirelessly transmits data to anotherapparatus through an antenna (not illustrated). The reception unit 562wirelessly receives data wirelessly transmitted from another apparatusthrough an antenna (not illustrated). The instruction input unit 570includes a keyboard, a switch and the like, and receives instructioninput from a user. The display unit 580 includes a liquid crystaldisplay and the like, and displays various types of information.

Next, an operation procedure of the remote control apparatus 30 will bedescribed, FIG. 19 is a flowchart illustrating the operation procedureof the remote control apparatus 30 in accordance with the presentpreferred embodiment.

(Step S701) The terminal detection unit 540 searches for anotherapparatus included in the image transmitting/receiving system 2. Then,the procedure proceeds to a process of step S702.

(Step S702) The recognition unit 531 determines whether an apparatuscapable of transmitting/receiving an image signal is included in theimage transmitting/receiving system 2 based on a result obtained bysearching for another apparatus in the process of step S701. When therecognition unit 531 determines that the apparatus capable oftransmitting/receiving the image signal is included in the imagetransmitting/receiving system 2, the procedure proceeds to a process ofstep S703. Otherwise, the procedure returns to the process of step S701.

(Step S703) The recognition unit 531 determines whether a referencesynchronization signal transmitted from another apparatus has beenreceived in tire reception unit 562 during a constant period. When therecognition unit 531 determines that a reference synchronization signaltransmitted from another apparatus has been received in the receptionunit 562, the procedure proceeds to a process of step S704. Otherwise,the procedure proceeds to a process of step S709.

(Step S704) The communication control unit 550 matches a receptionchannel of the reception unit 562 with a channel through which thereference synchronization signal has been transmitted in order toreceive the reference synchronization signal. Then, the procedureproceeds to a process of step S705.

(Step S705) The reception unit 562 receives a reference synchronizationsignal transmitted from the other apparatus. Furthermore, therecognition unit 531 recognizes a timing of a blanking interval based onthe reference synchronization signal received in the reception unit 562.Then, the procedure proceeds to a process of step S706.

(Step S706) The control unit 530 determines whether an instruction hasbeen input to the instruction input unit 570. When the control unit 530determines that an instruction has been input to the instruction inputunit 570, the procedure proceeds to a process of step S707. Otherwise,the control unit 530 performs the process of step S706 again.

(Step S707) The recognition unit 531 recognizes whether a current timepoint is a blanking interval based on the reference synchronizationsignal received in the reception unit 562 in the process of step S705.When the recognition unit 531 recognizes that the current time point isthe blanking interval, the procedure proceeds to a process of step S708.Otherwise, the recognition unit 531 performs the process of step S707again.

(Step S708) The communication control unit 550 controls the transmissionunit 561 to transmit a message based on the instruction input to theinstruction input unit 570 in the process of step S706 to anotherapparatus (the image transmitting apparatus 10 and the received imagedisplaying apparatus 20). Then, the procedure returns to the process ofstep S706.

(Step S709) The control unit 530 allows the reference synchronizationsignal generation unit 520 to generate the reference synchronizationsignal. The reference synchronization signal generation unit 520generates tire reference synchronization signal. Then, the procedureproceeds to a process of step S710. In addition, the referencesynchronization signal generation unit 520 continuously generates thereference synchronization signal until the remote control apparatus 30is powered off.

(Step S710) The communication control unit 550 acquires displayinformation (the size of image data and the number of frames) from theapparatus capable of transmitting/receiving art image signal based onthe result obtained by searching for the terminal detection unit 540 inthe process of step S701. Then, the procedure proceeds to a process ofstep S111.

(Step S711) The communication control unit 550 controls the transmissionunit 561 to transmit the reference synchronization signal generated bythe reference synchronization signal generation unit 520 to otherapparatuses included in the image transmitting/receiving system 2 in theform of a packet. Then, the procedure proceeds to a process of stepS712.

(Step S712) The control unit 530 determines whether the referencesynchronization signal has been transmitted to all channels. Mien thecontrol unit 530 determines that the reference synchronization signalhas been transmitted to all the channels, the procedure proceeds to aprocess of step S715. Otherwise, the procedure proceeds to a process ofstep S713.

(Step S713) The recognition unit 531 recognizes whether the blankinginterval has ended based on the reference synchronization signalgenerated by the reference synchronization signal generation unit 520.When the recognition unit 531 recognizes that the blanking interval hasended, the procedure proceeds to a process of step S715. Otherwise, theprocedure proceeds to a process of step S714.

(Step S714) The communication control unit 550 changes the communicationchannel of the transmission unit 561 to a channel through which thereference synchronization signal is not transmitted. Then, the procedurereturns to the process of step S712.

(Step S715) The communication control unit 550 returns die communicationchannel of the transmission unit 561 to the original channel. Then, theprocedure proceeds to a process of step S716.

(Step S716) The control unit 530 determines whether an instruction hasbeen input to the instruction input unit 570. When the control unit 530determines that the instruction has been input to the instruction inputunit 570, the procedure proceeds to a process of step S707. Otherwise,the control unit 530 performs the process of step S706 again.

(Step S717) The recognition unit 531 recognizes whether a current timepoint is a blanking interval based on the reference synchronizationsignal generated by the reference synchronization signal generation unit520. When the recognition unit 531 recognizes that the current timepoint is the blanking interval, the procedure proceeds to a process ofstep S718. Otherwise, the recognition unit 531 performs the process ofstep S717 again.

(Step S718) The communication control unit 550 controls the transmissionunit 561 to transmit a message based on the instruction input to theinstruction input unit 570 in the process of step S716 to anotherapparatus (the image transmitting apparatus 10 and the received imagedisplaying apparatus 20). Then, the procedure returns to the process ofstep S711.

In the case in which the aforementioned processes of step S701 to stepS718 are performed, when another apparatus transmits no referencesynchronization signal, the remote control apparatus 30 is able togenerate the reference synchronization signal and transmit the generatedreference synchronization signal to other apparatuses in the blankinginterval. Furthermore, the other apparatuses having received thereference synchronization signal are able to recognize the image signaltransmission timing and the blanking interval based on the referencesynchronization signal.

Next, a detailed example when switching a connection between the imagetransmitting apparatus 10 and the received image displaying apparatus 20will be described. FIG. 20 is a sequence diagram representing anoperation procedure when switching a connection between the imagetransmitting apparatus 10 and the received image displaying apparatus 20in accordance with the present preferred embodiment. A vertical axisindicates the passage of time. FIG. 20 illustrates a detailed example ofthe case in which, when the image transmitting apparatus 10-2 transmitsan image signal to the received image displaying apparatuses 20-2 and20-3 using a communication channel CH2, and the image transmittingapparatus 10-3 transmits an image signal to the received imagedisplaying apparatus 20-4 using a communication channel CH3, adestination to which the image transmitting apparatus 10-3 transmits animage signal is switched to the received image displaying apparatus 20-3based on a switching instruction of the remote control apparatus 30.

(Step S801) The image transmitting apparatus 10-2 transmits an imagesignal to the received image displaying apparatuses 20-2 and 20-3, andthe image transmitting apparatus 10-3 transmits an image signal to thereceived image displaying apparatus 20-4. In addition, in FIG. 20, thetiming at which the image transmitting apparatus 10-2 transmits theimage signal to the received image displaying apparatuses 20-2 and 20-3is different from the timing at which the image transmitting apparatus10-3 transmits the image signal to the received image displayingapparatus 20-4. However, this is for illustrative purposes only, and theimage transmitting apparatus 10-2 and the image transmitting apparatus10-3 actually transmit the image signals at the same timing.

(Step S802) The instruction input unit 570 of the remote controlapparatus 30 receives the input of an instruction for switching adestination to which the image transmitting apparatus 10-3 transmits animage signal to the received image displaying apparatus 20-3.

(Step S803) The remote control apparatus 30 transmits a switchinginstruction message to the image transmitting apparatus 10-3.

(Step S804) The remote control apparatus 30 transmits a disconnectioninstruction message to the received image displaying apparatus 20-4.

(Step S805) The received image displaying apparatus 20-4 transmits thedisconnection instruction message to the image transmitting apparatus10-3, and then disconnects a connection with the image transmittingapparatus 10-3. Furthermore, the image transmitting apparatus 10-3disconnects a connection with the received image displaying apparatus20-4.

(Step S806) The received image displaying apparatus 20-4 transmits adisconnection completion message to the remote control apparatus 30.

(Step S807) The remote control apparatus 30 transmits a channel changeinstruction message to the image transmitting apparatus 10-3.

(Step S808) The remote control apparatus 30 and the image transmittingapparatus 10-3 switch a communication channel from tire CH3 to the CH2.

(Step S809) The remote control, apparatus 30 transmits a disconnectioninstruction message to the received image displaying apparatus 20-3.

(Step S810) The received image displaying apparatus 20-3 transmits thedisconnection instruction message to the image transmitting apparatus10-2, and then disconnects a connection with the image transmittingapparatus 10-2. Furthermore, the image transmitting apparatus 10-2disconnects a connection with the received image displaying apparatus20-3.

(Step S811) The received image displaying apparatus 20-3 transmits adisconnection completion message to the remote control apparatus 30.

(Step S812) The remote control apparatus 30 transmits connection settinginformation of the received image displaying apparatus 20-3 to the imagetransmitting apparatus 10-3.

(Step S813) The image transmitting apparatus 10-3 prepares a connectionwith the received image displaying apparatus 20-3 based on theconnection setting information transmitted in the process of step S812,and then transmits a preparation completion message to the remotecontrol apparatus 30.

(Step S814) The remote control apparatus 30 transmits a message forinstructing a connection with the received image displaying apparatus20-3 to the image transmitting apparatus 10-3.

(Step S815) The image transmitting apparatus 10-3 performs acommunication connection with the received image displaying apparatus20-3, and then transmits a connection completion message to the remotecontrol apparatus 30.

(Step S816) The received image displaying apparatus 20-4 transmitsinformation specifying a channel (a free channel) to be used later bythe received image displaying apparatus 20-4 to the remote controlapparatus 30, changes a communication channel to the free channel, andthen waits for a connection.

(Step S817) The remote control apparatus 30 updates a communicationchannel, which is stored in the pairing list and used by the receivedimage displaying apparatus 20-4, based on the information received inthe process of step S816 and specifying the channel (the free channel)to be used later by the received image displaying apparatus 20-4.

(Step S818) The image transmitting apparatuses 10-2 and 10-3, thereceived image displaying apparatuses 20-2 to 20-4, and the remotecontrol apparatus 30 perform update processes of pairing lists.

(Step S819) After the blanking interval ends, the image transmittingapparatus 10-2 transmits the image signal to the received imagedisplaying apparatus 20-2, and the image transmitting apparatus 10-3transmits the image signal to the received image displaying apparatus20-3. In addition, in FIG. 20, the timing at which the imagetransmitting apparatus 10-2 transmits the image signal to the receivedimage displaying apparatus 20-2 is different from the timing at whichthe image transmitting apparatus 10-3 transmits the image signal to thereceived image displaying apparatus 20-3. However, this is forillustrative purposes only, and the image transmitting apparatus 10-2and the image transmitting apparatus 10-3 actually transmit the imagesignals at the same timing.

As with the aforementioned processes of step S801 to step S819, whenswitching a connection destination apparatus, the image transmittingapparatuses 10, the received image displaying apparatuses 20, and theremote control apparatus 30 included in the image transmitting/receivingsystem 2 perform the transmission/reception of data required in order toswitch the connection destination apparatus during the blankinginterval. Consequently, it is possible to perform the switching of acommunication connection without influencing the transmission/receptionof an image signal.

As described above, according to the present preferred embodiment, theremote control apparatus 30 included in the image transmitting/receivingsystem 2 transmits the reference synchronization signal indicating thetransmission timing of the image signal to the image transmittingapparatuses 10. Then, all the image transmitting apparatuses 10 includedin the image transmitting/receiving system 2 transmit tire image signalbased on the reference synchronization signal. In this way; all theimage transmitting apparatuses 10 included in the imagetransmitting/receiving system 2 are able to allow the timing at whichthe image signal is transmitted to synchronize with the timing (theblanking interval) at which the image signal is not transmitted.Furthermore, when switching a connection destination apparatus, theimage transmitting apparatuses 10, the received image displayingapparatuses 20, and the remote control apparatus 30 included in theimage transmitting/receiving system 2 perform the transmission/receptionof data required in order to switch the connection destination apparatusduring the blanking interval. Consequently; it is possible to performthe switching of a communication connection without influencing thetransmission/reception of an image signal.

So far, the first preferred embodiment to the fifth preferred embodimentof the present invention have been described in detail with reference tothe accompanying drawings. However, detailed configurations are notlimited to these preferred embodiments. For example, a design and thelike within the range without departing from the scope of the presentinvention may also be included.

For example, in the aforementioned preferred embodiments, the imagetransmitting/receiving system 1 includes three image transmittingapparatuses 10 and four received image displaying apparatuses 20.However, the present invention is not limited thereto. For example, theimage transmitting/receiving system 1 may include one or more imagetransmitting apparatuses 10 and one or more received image displayingapparatuses 20. Furthermore, in the aforementioned preferredembodiments, the image transmitting/receiving system 2 includes threeimage transmitting apparatuses 10, four received image displayingapparatuses 20, and one remote control apparatus 30. However, thepresent invention is not limited thereto. For example, the imagetransmitting/receiving system 2 may include one or more imagetransmitting apparatuses 10, one or more received image displayingapparatuses 20, and one or more remote control apparatuses 30.

The present invention can be extensively applied to an imagetransmitting/receiving system, an image transmitting apparatus, areceived image displaying apparatus, and a wireless control apparatus,and can perform the switching of a communication connection withoutinfluencing the transmission/reception of an image signal.

According to the image transmitting/receiving system of a preferredembodiment of the present invention, it is possible to start thedisconnection process of wireless communication within the period of thevertical blanking interval, so that it is possible to perform theswitching of a communication connection without influencing thetransmission/reception of an image signal.

According to the image transmitting apparatus of a preferred embodimentof the present invention, it is possible to start the disconnectionprocess of wireless communication within the period of the verticalblanking interval, so that it is possible to perform the switching of acommunication connection without influencing the transmission/receptionof an image signal.

According to the received image displaying apparatus of a preferredembodiment of the present invention, it is possible to start thedisconnection process of wireless communication within the period of thevertical blanking interval, so that it is possible to perform theswitching of a communication connection without influencing thetransmission/reception of an image signal.

According to the wireless apparatus of a preferred embodiment of thepresent invention, it is possible to wirelessly transmit the referencesynchronization signal to another apparatus and for the other apparatushaving received the reference synchronization signal to start thedisconnection process of wireless communication based on the referencesynchronization signal, so that it is possible to perform the switchingof a communication connection without influencing thetransmission/reception of an image signal.

According to the image transmitting/receiving method of a preferredembodiment of the present invention, it is possible to start thedisconnection process of wireless communication within the verticalblanking interval, so that it is possible to perform the switching of acommunication connection without influencing the transmission/receptionof an image signal.

What is claimed is:
 1. An image transmitting/receiving systemcomprising: a plurality of image transmitting apparatuses each of whichcontinuously wirelessly transmits continuously captured frame images ina captured order; and a plurality of received image displayingapparatuses each of which continuously wirelessly receives the frameimages continuously wirelessly transmitted by the plurality of imagetransmitting apparatuses and continuously displays the received frameimages in the captured order, wherein the image transmitting apparatuscomprises: a first wireless communication unit that wirelessly transmitsthe frame image to the received image displaying apparatus, which hasestablished a wireless communication connection with the imagetransmitting apparatus, in synchronization with a referencesynchronization signal, the received image displaying apparatuscomprises: a second wireless communication unit that wirelessly receivesthe frame images transmitted from the image transmitting apparatushaving established a wireless communication connection with the receivedimage displaying apparatus; and a display unit that displays the frameimages, which have been wirelessly received in the wirelesscommunication unit, in the captured order of the frame images, at leastone apparatus of the image transmitting apparatus and the received imagedisplaying apparatus included in the image transmitting/receiving systemcomprises: a reference synchronization signal generation unit thatgenerates a reference synchronization signal; and a control unit thatcontrols the reference synchronization signal generation unit togenerate the reference synchronization signal and controls the firstwireless communication unit to wirelessly transmit the referencesynchronization signal to another apparatus included in the imagetransmitting/receiving system when the second wireless communicationunit does not receive the reference synchronization signal within aconstant period, and at least one of the image transmitting apparatusand the received image displaying apparatus comprises: a blankinginterval recognition unit that recognizes a vertical blanking intervalof the frame image; and a disconnection control unit that controls thefirst or second wireless communication unit to start a disconnectionprocess of wireless communication within a period of the verticalblanking interval recognized by the blanking interval recognition unit.2. The image transmitting/receiving system according to claim 1, whereinthe disconnection control unit, which is provided in the at least one ofthe image transmitting apparatus and the received image displayingapparatus, controls the first or second wireless communication unit notto perform the disconnection process outside of the vertical blankinginterval.
 3. The image transmitting/receiving system according to claim1, wherein the blanking interval recognition unit recognizes thevertical blanking interval based on the frame image or the referencesynchronization signal.
 4. An image transmitting apparatus in an imagetransmitting/receiving system that comprises: a plurality of imagetransmitting apparatuses each of which continuously wirelessly transmitscontinuously captured frame images in a captured order; and a pluralityof received image displaying apparatuses each of which continuouslywirelessly receives the frame images continuously wirelessly transmittedby the plurality of image transmitting apparatuses and continuouslydisplays the received frame images in the captured order, the imagetransmitting apparatus comprising: a wireless communication unit thatwirelessly transmits the frame image to the received image displayingapparatus, which has established a wireless communication connectionwith the image transmitting apparatus, in synchronization with areference synchronization signal; a reference synchronization signalgeneration unit that generates a reference synchronization signal; acontrol unit that controls the reference synchronization signalgeneration unit to generate the reference synchronization signal andcontrols the wireless communication unit to wirelessly transmit thereference synchronization signal to another apparatus included in theimage transmitting/receiving system when the wireless communication unitdoes not receive the reference synchronization signal within a constantperiod; a blanking interval recognition unit that recognizes a verticalblanking interval of the frame image; and a disconnection control unitthat controls the wireless communication unit to start a disconnectionprocess of wireless communication within a period of the verticalblanking interval recognized by the blanking interval recognition unit.5. The image transmitting apparatus according to claim 4, wherein thecontrol unit controls the wireless communication unit to transmit thereference synchronization signal within the vertical blanking interval.6. The image transmitting apparatus according to claim 4, furthercomprising: a detection unit that detects a plurality of communicationchannels used when another image transmitting apparatus included in theimage transmitting/receiving system wirelessly transmits the frameimage, wherein the control unit controls the wireless communication unitto transmit the reference synchronization signal through eachcommunication channel detected by the detection unit.
 7. The imagetransmitting apparatus according to claim 6, wherein, when the detectionunit detects the plurality of communication channels, the control unitcontrols the wireless communication unit to transmit the referencesynchronization signal through only some of the plurality ofcommunication channels detected by the detection unit, in a singlevertical blanking interval.
 8. The image transmitting apparatusaccording to claim 7, wherein the wireless communication unit iscontrolled to transmit the reference synchronization signal through oneof the plurality of communication channels detected by the detectionunit, in the single vertical blanking interval.
 9. The imagetransmitting apparatus according to claim 4, further comprising: aninstruction receiving unit that receives an instruction for addition,modification, and deletion of a transmission destination of the frameimage, wherein, when the instruction receiving unit receives theInstruction, the disconnection control unit controls the wirelesscommunication unit to start the disconnection process.
 10. The imagetransmitting apparatus according to claim 9, further comprising: anoperation unit that receives an operation by a user, wherein theinstruction receiving unit receives the instruction based on theoperation received in the operation unit.
 11. The image transmittingapparatus according to claim 9, wherein the instruction receiving unitreceives the instruction from another apparatus included in the imagetransmitting/receiving system through the communication unit.
 12. Theimage transmitting apparatus according to claim 4, wherein thedisconnection control unit controls the wireless communication unit notto perform the disconnection process outside of the vertical blankinginterval.
 13. A received image displaying apparatus in an imagetransmitting/receiving system that comprises: a plurality of imagetransmitting apparatuses each of which continuously wirelessly transmitscontinuously captured frame images in a captured order; and a pluralityof received image displaying apparatuses each of which continuouslywirelessly receives the frame images continuously wirelessly transmittedby the plurality of image transmitting apparatuses and continuouslydisplays the received frame images in the captured order, the receivedimage displaying apparatus comprising: a wireless communication unitthat wirelessly receives the frame images from the image transmittingapparatus having established a wireless communication connection withthe received image displaying apparatus; a display unit that displaysthe frame images wirelessly received in the wireless communication unit,in a captured order of the frame images; a reference synchronizationsignal generation unit that generates a reference synchronizationsignal; a control unit that controls the reference synchronizationsignal generation unit to generate the reference synchronization signaland controls the wireless communication unit to wirelessly transmit thereference synchronization signal to another apparatus included in theimage transmitting/receiving system when the wireless communication unitdoes not receive the reference synchronization signal within a constantperiod; a blanking interval recognition unit that recognizes a verticalblanking interval of the frame image; and a disconnection control unitthat controls the wireless communication unit to start a disconnectionprocess of wireless communication within a period of the verticalblanking interval recognized by the blanking interval recognition unit.14. The received image displaying apparatus according to claim 13,wherein the wireless communication unit wirelessly receives the frameimages in a form of packet data, and the reference synchronizationsignal generation unit generates the reference synchronization signalbased on packet data, which indicates final data of each frame of theframe images, among the packet data wirelessly received in the wirelesscommunication unit.
 15. The received image displaying apparatusaccording to claim 13, wherein the control unit controls the wirelesscommunication unit to wirelessly transmit the reference synchronizationsignal generated by the reference synchronization signal generation unitaccording to packet data indicating a response for packet data, whichindicates final data of each frame of the frame images, among the packetdata wirelessly received in the wireless communication unit.
 16. Thereceived image displaying apparatus according to claim 13, wherein thewireless communication unit wirelessly receives the frame images in aform of packet data, and the blanking interval recognition unitrecognizes the vertical blanking interval of the frame image based onwhether the packet data wirelessly received in the wirelesscommunication unit is packet data indicating final data of each frame ofthe frame images.
 17. The received image displaying apparatus accordingto claim 13, further comprising: a detection unit that detects aplurality of communication channels used when another image transmittingapparatus included in the image transmitting/receiving system wirelesslytransmits the frame image, wherein the control unit controls thewireless communication unit to transmit the reference synchronizationsignal through each communication channel detected by the detectionunit.
 18. The received image displaying apparatus according to claim 17,wherein, when the detection unit detects the plurality of communicationchannels, the control unit controls the wireless communication unit totransmit the reference synchronization signal through only some of theplurality of communication channels detected by the detection unit, in asingle vertical blanking interval.
 19. The received image displayingapparatus according to claim 18, wherein the control unit controls thewireless communication unit to transmit the reference synchronizationsignal through one of the plurality of communication channels detectedby the detection unit, in the single vertical blanking interval.
 20. Thereceived image displaying apparatus according to claim 13, furthercomprising: an instruction receiving unit that receives an instructionfor addition, modification, and deletion of a transmission destinationof the frame image, wherein, when the instruction receiving unitreceives the instruction, the disconnection control unit controls thewireless communication unit to start the disconnection process.
 21. Thereceived image displaying apparatus according to claim 20, furthercomprising: an operation unit that receives an operation by a user,wherein the instruction receiving unit receives the instruction based onthe operation received in the operation unit.
 22. The received imagedisplaying apparatus according to claim 20, wherein the instructionreceiving unit receives the instruction from another apparatus includedin the image transmitting/receiving system through the communicationunit.
 23. The received image displaying apparatus according to claim 13,wherein the disconnection control unit controls the wirelesscommunication unit not to perform the disconnection process outside ofthe vertical blanking interval.
 24. A wireless control apparatus in animage transmitting/receiving system that comprises: a plurality of imagetransmitting apparatuses each of which continuously wirelessly transmitscontinuously captured frame images in a captured order; a plurality ofreceived image displaying apparatuses each of which continuouslywirelessly receives the frame images continuously wirelessly transmittedby the plurality of image transmitting apparatuses and continuouslydisplays the received frame images in the captured, order; and thewireless control apparatus that instructs the image transmittingapparatus to wirelessly communicate with the received image displayingapparatus serving as a transmission destination of the frame image andinstructs the received image displaying apparatus to wirelesslycommunicate with the image transmitting apparatus serving as atransmission source of the frame image, the wireless control apparatuscomprising: a wireless communication unit that wirelessly communicateswith the image transmitting apparatus and the received image displayingapparatus; a reference synchronization signal generation unit thatgenerates a reference synchronization signal; and a control unit thatcontrols the reference synchronization signal generation unit togenerate the reference synchronization signal and controls the wirelesscommunication unit to wirelessly transmit the reference synchronizationsignal to another apparatus included in the image transmitting/receivingsystem when the wireless communication unit does not receive thereference synchronization signal within a constant period.
 25. Thewireless control apparatus according to claim 24, wherein the wirelesscontrol apparatus comprises: an instruction receiving unit that receivesan instruction for addition, modification, and deletion of a combinationof the apparatus serving as the transmission destination of the frameimage and the apparatus serving as the transmission source of the frameimage; and a disconnection instruction control unit that controls thewireless communication unit to transmit an instruction for starting adisconnection process of wireless communication to the apparatus of thecombination received in the instruction receiving unit when theinstruction receiving unit receives the instruction.
 26. An imagetransmitting/receiving method in an image transmitting/receiving systemthat comprises; a plurality of image transmitting apparatuses each ofwhich continuously wirelessly transmits continuously captured frameimages in a captured order; and a plurality of received image displayingapparatuses each of which continuously wirelessly receives the frameimages continuously wirelessly transmitted by the plurality of imagetransmitting apparatuses and continuously displays the received frameimages in the captured order, the image transmitting/receiving methodcomprising: a wireless transmission step of wirelessly transmitting, bya wireless communication unit of the image transmitting apparatus, theframe image to the received image displaying apparatus, which hasestablished a wireless communication connection with the imagetransmitting apparatus, in synchronization with a referencesynchronization signal; a wireless reception step of wirelesslyreceiving, by a wireless communication unit of the received imagedisplaying apparatus, the frame image transmitted from the imagetransmitting apparatus having established a wireless communicationconnection with the received image displaying apparatus; a display stepof displaying, by a display unit of the received image displayingapparatus, the frame images, which have been wirelessly received in thewireless communication unit, in the captured order of the frame images;a reference synchronization signal generation step of generating, by areference synchronization signal generation unit of at least one of theimage transmitting apparatus and the received image displaying apparatusincluded in the image transmitting/receiving system, a referencesynchronization signal; a control step of controlling, by a control unitof at least one of the image transmitting apparatus and the receivedimage displaying apparatus included in the image transmitting/receivingsystem, the reference synchronization signal generation unit to generatethe reference synchronization signal and controlling the wirelesscommunication unit, to wirelessly transmit the reference synchronizationsignal to another apparatus included in the image transmitting/receivingsystem when the wireless communication unit does not receive thereference synchronization signal within a constant period; a blankinginterval recognition step of recognizing, by a blanking intervalrecognition unit of at least one of the image transmitting apparatus andthe received image displaying apparatus, a vertical blanking interval ofthe frame image; and a disconnection control step of controlling, by adisconnection control unit of at least one of the image transmittingapparatus and the received image displaying apparatus, the wirelesscommunication unit to start a disconnection process of wirelesscommunication within a period of the vertical blanking intervalrecognized by the blanking interval recognition unit.